The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The head disk assembly includes at least one disk (such as a magnetic disk, magneto-optical disk, or optical disk), a spindle motor for rotating the disk, and a head stack assembly (HSA). The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly includes at least one head, typically several, for reading and writing data from and to the disk. In an optical disk drive, the head may include a mirror and objective lens for reflecting and focusing a laser beam on to a surface of the disk. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk.
The spindle motor typically includes a rotatable spindle motor hub, a magnet attached to the spindle motor hub, and a stator. Various coils of the stator are selectively energized to form an electromagnetic field that pulls/pushes on the magnet, thereby imparting a rotational motion onto the spindle motor hub. Rotation of the spindle motor hub results in rotation of the attached disks.
The head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit assembly. A conventional “rotary” or “swing-type” actuator assembly typically includes an actuator having an actuator body. The actuator body has a pivot bearing cartridge to facilitate rotational movement of the actuator assembly. One or more actuator arms extend from the actuator body. Each actuator arm supports at least one head gimbal assembly that includes a head. An actuator coil is supported by the actuator body opposite the actuator arms. The actuator coil is configured to interact with one or more magnets, typically a pair, to form a voice coil motor. The printed circuit board assembly controls current passing through the actuator coil that results in a torque being applied to the actuator.
A latching mechanism is provided to facilitate latching of the actuator in a parked position when the heads are not being used to interact with the tracks on the disk. In the parked position, the actuator is positioned with the heads either at an inner diameter (ID) of the disk or at or beyond an outer diameter (OD) of the disk such as upon a ramp. A crash stop coupled to the disk drive base is provided to limit rotation of the actuator in a given direction. Another crash stop may be provided to limit actuator rotation in an opposite rotational direction. The latching mechanism may additionally function as one of the crash stops.
Depending upon the particular latch configuration, the latch may be biased in either an open or closed position. The latch may include a plastic latch body and a biasing element such as a spring or a ferromagnetic material. A ferromagnetic biasing element magnetically interacts with the magnet of the actuator voice coil motor so as to bias the angular position of the actuator. The biasing element may be coupled to the latch body by being press-fit within a cavity formed in the latch body. Use of adhesives to retain the biasing element in the cavity is often undesirable from an assembly and/or a contamination point of view. Latching and crash-stop operation subjects the latch to repeated impacts. As a result the biasing element may become dislodged or loosened.
Accordingly, it is contemplated that there is need in the art for an improved latch biasing element configuration for maintaining a relatively secure attachment and for facilitating an ease of assembly.